linux-kernel - [PATCH v2] x86/platform/uv: Dont use smp_processor

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Date:   Mon, 23 May 2022 11:45:21 -0500
From:   Mike Travis <mike.travis@....com>
To:     Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Ingo Molnar <mingo@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Steve Wahl <steve.wahl@....com>, x86@...nel.org
Cc:     Mike Travis <mike.travis@....com>,
        Dimitri Sivanich <dimitri.sivanich@....com>,
        stable@...r.kernel.org, Andy Shevchenko <andy@...radead.org>,
        Darren Hart <dvhart@...radead.org>,
        "H. Peter Anvin" <hpa@...or.com>,
        Russ Anderson <russ.anderson@....com>,
        linux-kernel@...r.kernel.org, platform-driver-x86@...r.kernel.org
Subject: [PATCH v2] x86/platform/uv: Dont use smp_processor_id while preemptible

To avoid a "BUG: using smp_processor_id() in preemptible" debug
warning message, disable preemption around use of the processor id.

Signed-off-by: Mike Travis <mike.travis@....com>
Reviewed-by: Steve Wahl <steve.wahl@....com>
Reviewed-by: Dimitri Sivanich <dimitri.sivanich@....com>
Cc: stable@...r.kernel.org
---
v2: Add Cc: stable tag
---
 arch/x86/platform/uv/uv_time.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/arch/x86/platform/uv/uv_time.c b/arch/x86/platform/uv/uv_time.c
index 54663f3e00cb..094190814a28 100644
--- a/arch/x86/platform/uv/uv_time.c
+++ b/arch/x86/platform/uv/uv_time.c
@@ -275,14 +275,17 @@ static int uv_rtc_unset_timer(int cpu, int force)
  */
 static u64 uv_read_rtc(struct clocksource *cs)
 {
-	unsigned long offset;
+	unsigned long offset, time;
+	unsigned int cpu = get_cpu();
 
 	if (uv_get_min_hub_revision_id() == 1)
 		offset = 0;
 	else
-		offset = (uv_blade_processor_id() * L1_CACHE_BYTES) % PAGE_SIZE;
+		offset = (uv_cpu_blade_processor_id(cpu) * L1_CACHE_BYTES) % PAGE_SIZE;
 
-	return (u64)uv_read_local_mmr(UVH_RTC | offset);
+	time = (u64)uv_read_local_mmr(UVH_RTC | offset);
+	put_cpu();
+	return time;
 }
 
 /*
-- 
2.26.2